The Globe
How to describe where you are, and how to find new places.

Intelligence Competition
• To find who is smarter, males or females , we are going to conduct a scientific experiment. I will give the name of a place in Arizona. When you have located that place on the map, raise your hand . This is a timed test. The first 5 times will count for the team score. Lowest times win. Ladies first. No cheating!

Ladies find -
• Sasabe Arizona

Guys find -
• Holy Joe Peak

HINT!!!
Look in I 9

You need -
Coordinates (= two numbers)
• One set across
• One set down
• Start at logical point - on flat map, upper left corner (just like reading.)
• Use letters or numbers
• I 9 BINGO!

Can we do this for the
Earth?
(Photo of Earth here)

We have a problem!
• Spheres don’t have a logical starting point.

BUT, The Earth rotates on its axis.
This gives us
Two logical
Starting points.
North Pole
(How would
You know if
You were
There?)
Axis
South Pole

You could then draw lines from one pole to the other.

Now, if you divide each of those lines in half and draw a line through the midpoints…
You get the
Equator

Next, draw lines around the
Earth parallel to the equator .

Finally, we have our grid !

Remember from math -
Circles are divided into 360 degrees .

Latitude
• Measures degrees north/south
– also called parallels
• Starting point: Equator 0º
• Ending point: Poles 90 ° N,S
• Equator separates
North/South Hemispheres
• Equator is a great circle
– the only parallel great circle
– What in the world is a GREAT
CIRCLE ?

A great circle is the edge of a cut through the Earth that passes through Earth’s center

Longitude
• Measures degrees east/west
– also called meridians
• Starting point:
Prime Meridian 0º
• Ending point: International
Date Line 180º
• Separates East/West hemispheres
– every meridian and the one opposite make a great circle

Each Degree of Latitude
(or Longitude at the Equator)
• Represents ~69 miles
• (360 x 69 = 24,840mi)
• To be more precise:
– each degree
• 60 minutes
• ~1.15 miles
– each minute
• 60 seconds
• ~101 feet

Distance for a degree of longitude varies

Written Form latitude , longitude degrees minutes (&seconds)
Phoenix: 33 º 26 ’ N , 112 º 04 ’ W
MCC: 33 º 25 ’ N , 111 º 49 ’ W

International Meridian
Conference
• 1884
• 27 nations
• Established Royal Observatory at
Greenwich England as the Prime
Meridian

Map Projections
• A globe is not always the best representation of the Earth
– Doesn’t show local detail
– Lacks convenience - not portable

Map Projections
• But a globe is the only true representation of:
– direction
– area
– shape
– distance